Audio tape players have a motor for driving the tape hopefully at a constant rate. A common problem with such devices is that the motor speed tends to undulate about a desired rate and the sound frequency wavers from its ideal. Depending on the frequency of the deviation, this sound aberration is called wow or flutter. To assure acceptable quality of tape players at the time of manufacture or purchase, the wow and flutter is measured to determine whether the deviation is within prescribed standards. The measurement entails playing a tape of a constant tone and analyzing the resulting tone for frequency deviations.
Typically instruments for measuring wow and flutter comprise an FM detector and an analog low pass filter to process the tone signal by isolating the deviation, and a meter to indicate the deviation. In a system for checking a large number of tape decks, a test controller comprising a desktop computer controls the wow and flutter detector and monitors the output. The stand alone detector combined with a test controller is expensive.